抄録
In order to establish an experimental model of chronic interstitial pneumonia in dogs, that can be used for physiological research, intramuscular injections of herbicide paraquat were administered. Gramoxone (containing 24% paraquat) and pure paraquat solution were used. As most dogs died after the large dose single injection method, a small dose 4 injection method was designed. Initial dose was 0.5mg/kg (1% paraquat solution), and for the remaining three injections, 0.5 or 1.0mg/kg dose was selected according to weight loss and general condition. The pathological findings of the lung were examined at four points. The acute change induced by cells and the single injection method was severe destruction of alveolar structure and excessive proliferation of interstitial fibers, i. e. acute intestitial pneumonia. To study the chronic changes induced by the 4-time injection method, dogs were sacrificed at the 69th day after the final injection on average. Alveolar wall thickening and type II pneumocyte hyperplasia and interstitial cell proliferation were seen. Intra-alveolar infiltration of cells and fluid was rare. Partial destruction of alveolar structure was recognized. One dog had granulomatous change and eosinophilic intra-alveolar exudate.
Physiological measurements (VC, RV, TLC) before and after the injections were performed. The pressure-volume curve was plotted (expiratory phase). K of the pressure-volume curve was calculated according to Salazar's method. VC, RV, TLC and K before and after the injection were compared. Statistically significant differences were recognized between them.
Using the small dose 4 injection method, we induced chronic interstitial pneumonia of slight degree in the dogs. In order to induce more definite pulmonary involvement, a higher injection dose would be needed, but mortality rate of the dogs would inevitably increase.
